Pain
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Comparative Study
Cold and heat pain assessment of the human oesophagus after experimental sensitisation with acid.
The aim of the present study was to investigate the effect of thermal stimulation of the oesophagus before and after sensitisation with acid. In 17 healthy subjects a stimulation bag was used to re-circulate water at 5 and 60 degrees C for up to 90 s in the lower part of the oesophagus. The area under the temperature curve was used to assess the caloric load. ⋯ After sensitisation the words used to describe the sensations to heat pain stimuli shifted from a warmth quality towards a more burning quality in most subjects. This multi-modal sensory testing study showed that acid sensitises the oesophagus to heat but not to cold pain. This may account for the modality-specific symptoms and hypersensitivity reported in patients suffering from, e.g. gastro-oesophageal reflux disease.
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Comparative Study
Neuroelectric source imaging of steady-state movement-related cortical potentials in human upper extremity amputees with and without phantom limb pain.
Whereas several studies reported a close relationship between changes in the somatotopic organization of primary somatosensory cortex and phantom limb pain, the relationship between alterations in the motor cortex and amputation-related phenomena has not yet been explored in detail. This study used steady-state movement-related cortical potentials (MRCPs) combined with neuroelectric source imaging to assess the relationship of changes in motor cortex and amputation-related phenomena such as painful and non-painful phantom and residual limb sensations, telescoping, and prosthesis use. Eight upper limb amputees were investigated. ⋯ Non-painful phantom sensations as well as painful and non-painful residual limb sensations were unrelated to motor cortical reorganization. A higher amount of motor reorganization was associated with less daily prosthesis use, which also tended to be related to more severe phantom limb pain. These results extend previous findings of a positive relationship between somatosensory reorganization and phantom limb pain to the motor domain and suggest a potential positive effect of prosthesis use on phantom limb pain and cortical reorganization.
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Comparative Study
Sensitization to bradykinin B1 and B2 receptor activation in UV-B irradiated human skin.
Bradykinin B1 and B2 receptors contribute to nociceptor sensitization under inflammatory conditions. Here, we examined the vascular inflammatory responses and nociceptive effects resulting from activation of B1 and B2 receptors in healthy and UV-B irradiated skin in human volunteers. The B1 receptor agonist des-Arg(10)-Kallidin (10(-6)-10(-3)M) and the B2 receptor agonist bradykinin (10(-9)-10(-4)M) were administered by dermal microdialysis to the ventral thigh. ⋯ In normal skin, both B1 and B2 receptor activation dose-dependently evoked pain, vasodilatation and protein extravasation. In UV-B irradiated skin, pain sensation and axon reflex vasodilatation were enhanced by both B1 and B2 agonists, whereas local vasodilatation was increased only following B1 receptor activation. The UV-B irradiation did not enhance B1 and B2 receptor-induced protein extravasation indicating a differential sensitization of the neuronal, but not the vascular response.
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Comparative Study
Mechanical allodynia and thermal hyperalgesia upon acute opioid withdrawal in the neonatal rat.
Upon withdrawal from opioids many patients experience a heightened sensitivity to stimuli and an exaggerated pain response. We present evidence that neonatal rats exhibit allodynia and hyperalgesia on acute opiate withdrawal. Postnatal 7 and 21 day rats were used to approximately model a full term human infant and a human child, respectively. ⋯ Spontaneous and precipitated withdrawal from a single acute administration of morphine produced mechanical allodynia and thermal hyperalgesia in postnatal day 7 rats and mechanical allodynia in postnatal day 21 rats. A higher dose of morphine was required to produce mechanical allodynia in postnatal day 21 versus 7 rats but this increase was independent of the analgesic efficacy of morphine at these two ages. The present work illustrates the need to examine the phenomenon of hypersensitivity upon opioid withdrawal in the human pediatric population.
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Comparative Study
Pain-related fear and daily functioning in patients with osteoarthritis.
There is growing evidence supporting the relationship between pain-related fear and functional disability in chronic musculoskeletal pain conditions. In osteoarthritis (OA) patients the role of pain-related fear and avoidance has received little research attention so far. The present study investigates the degree to which pain-related fear, measured with the Tampa Scale for Kinesiophobia (TSK), influences daily functioning in OA patients. ⋯ Radiological findings were not significant predictors and when compared to pain-related fear they were not significant. These findings underscore the importance of pain-related fear in daily functioning of OA patients. Therefore, treatment strategies aiming at reduction of pain-related fear in OA patients need to be developed and investigated.